What do you do with a dying space probe? That was the question facing Dr. Colleen Hartman '77 at NASA in the summer of 2003.

When the moment of truth came,
Colleen Hartman '77 didn't hesitate. "I don't think we have a
choice," she told the other scientists around the crowded conference table. "We have to protect Europa's ocean from contamination--which means we'll have to plunge Galileo into Jupiter."

It might sound like an excerpt from a sci-fi script, but it actually happened on a summer morning in 2003, when the 48-year-old astrophysicist decided the fate of one of the most successful space probes ever launched. The story of Galileo's final descent into the swirling gas giant that is Jupiter surely ranks as one of the most dramatic sagas in the history of solar system exploration--and who better to tell it than Hartman, for whom Galileo's remarkable success was the culmination of 22 action-packed years as a scientist and top administrator at the National Aeronautics and Space Administration?

"What took place last September 21 was the glorious end to a robotic creation that humans sent to a fascinating solar-system destination," says the upbeat and perpetually curious Hartman, once a Pomona zoology major. "The Galileo mission data-return will reveal more about Jupiter and its moons than any previous mission sent by any nation, and that leaves you with a terrific feeling of accomplishment."

Then, settling back in her office chair, she tells the story of Galileo's final days, just before the probe vanished forever into the boiling clouds of the Jovian atmosphere and Hartman herself embarked upon a major course change in her own brilliant career.

What Do You Do With a Dying Probe?

After 14 years, three billion miles and 34 fly-bys of Jupiter, the most successful planetary orbiter in the history of human space exploration was about to plunge into fiery oblivion. Nearly out of rocket propellant and increasingly in danger of wobbling out of control, the U.S. space probe known as Galileo had long since completed its key mission--sending back thousands of pages of data about our solar system's largest planet and its many moons.

No larger than a Ford Explorer and easily the most popular space-robot in the history of exploration, Galileo had reached the end of its lifespan. For the engineers, physicists and administrators at NASA a single question remained: Should the space scientists in Washington--assisted by their colleagues at the Jet Propulsion Lab (JPL) in Pasadena--allow the droid to plunge into the cauldron of Jupiter's atmosphere, where it would be vaporized in temperatures twice as hot as those on the surface of the sun? Or was there a more interesting way to dispose of a dying orbiter?

As June turned into July and the inevitable annihilation of the tiny-brained probe (its 1980s computer resembled an old-fashioned Apple II) approached, one other possibility remained. What if the scientists from NASA and JPL were to give the spacecraft a final rocket-nudge--just enough power to send it arcing toward Jupiter's most intriguing moon--the enigmatic Europa, which almost certainly contains an underground ocean that could provide a habitat for microbial life?

It was a tantalizing alternative. Already, during its many fly-bys of Europa and her sister "icy moons" (Ganymede, Callisto and Io), Galileo had collected convincing data to suggest that Europa's underground ocean might be able to support living organisms.

Sitting in her Washington office, Hartman crunched the numbers and pondered. Would it work? Did they have enough fuel? Was Galileo's orbit close enough to Europa's to allow the crash to take place on the oceanic moon instead of the giant planet?

Yes, it was possible. It could be done. And the decision would have to come from Hartman, who as director of NASA's Solar System Exploration Division would be responsible for deciding Galileo's fate. Assessing the possibilities, Hartman asked herself: Why not learn as much as possible about Europa and her mysterious ocean as the droid and its two dozen on-board instruments streaked toward a collision with the moon's icy crust?

But there was a problem.

When it comes to exploring the planets of our solar system, there is always a problem--a formidable (and sometimes disqualifying) hurdle that must be overcome in order to achieve your exploration goals.

In this case, the name of the problem was forward contamination. In space-talk, that refers to a scenario in which microbes from Earth hitch a ride on a spacecraft and take root on another planet or moon in the solar system. If that should happen, the Earth bugs would "contaminate" the "off-world"--forever changing it as a biological habitat and damaging it as a subject of study for Earthlings.

Could the NASA scientists afford to take a chance on forward contamination with Europa?

A Confab with the Planetary Protection Officer

Hartman reached for the phone, then dialed the number for a NASA administrator with the intriguing official title of "Planetary Protection Officer." For at least the 10th time, she would sit down with Dr. John Rummel, the veteran "exobiologist" (an expert on "off-world" life-forms) who's responsible for making sure that microbes from Earth space probes do not infect the celestial bodies they're sent to scrutinize.

Dr. Rummel was adamant. "I felt very strongly about this, and I advised Colleen that we couldn't take the risk," he said in a recent interview. "She's an extremely thoughtful scientist and she's also an extremely effective administrator. I think she was as determined as I am to protect the integrity of Europa's ocean, in case we later discover that microbial life exists there.

"We faced a very real risk of contaminating the [Jovian] moon, and I think that soon became clear in our discussions."

Although she was disappointed at the thought of missing out on a chance for an up-close look at enigmatic Europa, Hartman quickly concurred with the Planetary Protection chief's assessment of the situation. "John and I were in complete agreement about the necessity of plunging Galileo into Jupiter," she said recently in Washington. "Protecting Europa's oceans so that we can investigate them with NASA's Jupiter Icy Moons spacecraft [a planned future project] in their pristine state is of paramount importance.

"We must understand how life could arise in our solar system, and to do that, we need worlds that are uncontaminated."

For the orbiting droid, named after the great 17th-century astronomer, the die was now cast. At three minutes to noon (PDT) on September 21, 2003, Galileo's radio signals crackled briefly and then fell silent as the probe rocketed at more than 100,000 miles an hour into the blazing gases of Jupiter. Within a matter of moments, the 14-year-old robot had evaporated into the planet's immense atmosphere.

"Galileo was probably the most successful 'outer worlds' mission ever launched from Earth," says Hartman, ticking off the droid's accomplishments, including such mind-benders as flying within 50 miles of several Jovian moons and snapping photos of the first moon ever found to be orbiting an asteroid. "This spacecraft gave us some unbelievable discoveries, along with 14,000 photos and innumerable data-sets, as it flew past Jupiter and its satellites 34 times in a row without a hitch.

"I feel privileged to have been part of the project, but I should also point out that it had gotten underway long before I became director of Solar System Exploration. As far as I'm concerned, the project managers and scientists at the Jet Propulsion Lab in Pasadena were the real heroes of the Galileo mission--because they were the ones who 'baby-sat' the spacecraft through all its trials and tribulations."

A Fan of the Liberal Arts

When Hartman arrived on the Pomona campus back in September of 1973, she was already an ardent if youthful biologist who enjoyed nothing more than "scooping up a jarful of swamp water and putting it under the microscope and then going, 'Oh my gosh, there's an entire microcosm in that drop of water!'"

An enthusiastic zoology major from the get-go, she says she was "very surprised" when her favorite course turned out to be philosophy, of all things. "I took a course in Plato from Professor Jay Atlas, and he was an amazing teacher. He'd rush into class and tell us, 'Okay, this Plato guy is just killing me--we gotta talk!' And then he'd sit down and talk to you for an hour at a time about your understanding of one of the Socratic Dialogues, or a passage from The Republic.

"I wound up getting a degree in zoology, of course, and then later I went on and studied for a Ph.D. in physics, but I really think that philosophy course--along with several other liberal arts courses I took at Pomona--played a crucial role in my career as a scientist. Why? Because the liberal arts teach you where to look for things!

"As the years passed and I moved from one job to another at NASA, where I started way back in 1981 as a 'presidential management intern,' I found I wasn't afraid of learning new subjects, new disciplines. I really think the liberal arts taught me how to go about the business of learning new things--rather than just requiring me to memorize lots of data or perform lots of mechanical computations."

She pauses for a moment, reflecting on her two decades-plus of work at NASA, then cuts loose with her booming, signature laugh. "Here I am at the tender age of 48--and I'm starting all over again, at a brand-new federal agency! And instead of feeling intimidated, I feel confident and relaxed about this new challenge. I'm convinced that the liberal arts can help people to keep 're-inventing' themselves through the years, because they teach you how to think. And that's why I'm such a big fan of courses on Plato, or the 19th-century English novel. Those kinds of courses might sound specialized and narrow--but they're actually the right tools you need for a successful career."

The Most Fascinating Planet

Perhaps one reason Hartman still identifies so strongly with the little probe that could is that the final hours of its remarkable career coincided with a huge change in the trajectory of her own.

On Monday, September 23, 2003, just two days after Galileo's fiery demise, Hartman left NASA to take over as the new Deputy Assistant Administrator of the Satellite and Information Service at the National Oceanic and Atmospheric Administration (NOAA), headquartered in downtown Washington. Her new assignment: To oversee operations that will include everything from collecting space-based weather info to managing planet-wide databases aimed at studying such crucially important phenomena as global warming and soil erosion.

Today, she looks back on two decades at NASA--a career punctuated by numerous awards, including a coveted NASA Headquarters Outstanding Performance Award and two Goddard Center Director's Citations--with a mix of pride and nostalgia. Ask the pioneer why she would "give up the thrills of space flight" to become a satellite manager for the federal weather department, and she'll surprise you with her passionate but down-to-earth answer.

"I've been asked that question many times," she says with another bright laugh, "and my answer is always the same: I might have given up the nine planets, but I've gained the one we're standing on, and that's the most important one of all. Really, as far as I'm concerned, studying Earth's weather is no different from going to Pluto. If you stop and think about it, you realize that we actually know surprisingly little about our own planet. Example: Only a few years ago, we discovered bacteria living near hydrothermal vents, on the bottom of the ocean floor, at temperatures approaching the boiling point. And that discovery, along with others like it, showed us that life exists in much harsher environments than we ever dreamed possible, right here on Earth.

"After only a few weeks on this new job, I've already begun to discover that the most fascinating planet in the solar system may actually turn out to be our own!"

—Tom Nugent is a freelance journalist who lives in Hastings, Michigan.